Conventionally, when a semiconductor wafer (hereinafter, simply referred to as “wafer”) is subjected to grinding process to make an ultra-thin semiconductor wafer, a protection sheet is generally stuck on a circuit plane side thereof, and the protection sheet is peeled off after completion of mounting step on a ring frame. Since the wafer is extremely thin, special attention is required when peeling off the protection sheet.
In patent documents 1 and 2, a peeling apparatus and a peeling method of a protection sheet described above are disclosed. The documents propose such an arrangement that a plurality of rolls are combined so as to ensure a large peeling angle and the protection sheet can be peeled in a direction as parallel as possible relatively to a surface of the wafer, and thereby cracks or the like on the wafer are prevented.
[Patent document 1] Japanese Patent Application Laid-Open No. 2001-319906
[Patent document 2] Japanese Patent Application Laid-Open No. 2000-91281